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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 971 (Transfer Case - NVG 246-NP8) >> Diagnostic Information and Procedures >> DTC C0300: Rear Speed Sensor Malfunction >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

  1. 2:  This step tests to see if the malfunction is intermittent.
  2. 3:  This step tests the internal resistance of the propshaft speed sensor.
  3. 4:  This step tests to see if the propshaft speed sensor can generate a sufficient amount of AC voltage.
  4. 5:  This step tests the rear speed sensor low circuit for a short to ground, a high resistance, or an open.
  5. 6:  This step tests the rear speed sensor high circuit for a short to ground, a high resistance or an open.
  6. 7:  This step tests the rear speed sensor low circuit for a short to voltage.
  7. 8:  This step tests the rear speed sensor high circuit for a short to voltage.
  8. 9:  This step tests the rear speed sensor low circuit for a short to the rear speed sensor high circuit.
DTC C0300

Step Action Values Yes No
Schematic Reference:  Transfer Case Control Schematics  
Connector End View Reference:  Transfer Case Control Connector End Views  
1 Did you perform the Diagnostic System Check - Transfer Case? - Go to Step 2  Go to Diagnostic System Check - Transfer Case 
2 
  1. Drive the vehicle for a short test drive.
  2. With the scan tool, observe the value of the rear propshaft speed data parameter in the transfer case data list, while driving.
Does the RPM value vary while driving?		 - Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 3 
3 
  1. Turn the ignition OFF.
  2. Disconnect the transfer case rear propshaft speed sensor.
  3. Measure the resistance of the transfer case rear propshaft speed sensor.
Is the resistance reading within the specified values?		 1,300-2,700 Ω Go to Step 4  Go to Step 10 
4 
  1. Connect a DMM to the transfer case rear propshaft speed sensor.
  2. Block the front wheels.
  3. Place the transmission in neutral.
  4. Raise and support the rear axle so that the wheels turn freely.
  5. Hold one rear wheel while rotating the other rear wheel.
  6. Observing the AC voltage reading on the DMM
Is the voltage reading greater than the specified value?		 0.2-0.5 V AC Go to Step 5  Go to Step 10 
5 
  1. Disconnect the transfer case shift control module.
  2. Test the rear speed sensor low signal circuit for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 12  Go to Step 6 
6  Test the rear speed sensor high signal circuit for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 12  Go to Step 7 
7  Test the rear speed sensor low signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 12  Go to Step 8 
8  Test the rear speed sensor high signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 12  Go to Step 9 
9  Test the rear speed sensor high signal circuit for a short to the rear speed sensor low signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 12  Go to Step 11 
10 Replace the transfer case rear propshaft speed sensor. Refer to Transfer Case Speed Sensor Replacement - Right Rear .
Did you complete the repair?		 - Go to Step 12  -
11 Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement  and Transfer Case Control Module Reprogramming .
Did you complete the repair?		 - Go to Step 12  -
12
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC set?		 - Go to Step 2  System OK
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